This part of ISO/IEC 16500 provides a toolbox consisting of lower layer protocols and physical interfaces. Each tool is applicable at one or more of the reference points within the delivery system. The physical delivery media that have been identified for this version of ISO/IEC 16500-4 are copper pairs, coaxial cable, microwave, fiber and satellite. Removable information carrying physical media (e.g. optical discs and tapes) are not covered. The tools listed address the three parts of the delivery system, namely, the core network, the access network and the access-network-independent interface to the Set Top Unit (STU). Tools are also identified for the STU dataport interface and for a service provider system (SPS) internal network and an SPS/SPS core network.

Clause 6 specifies in detail the tools provided to digitize the physical media in the core network. In the case of a broadband core network, all these tools support high speed ATM transport. Clause 7 specifies in detail the tools provided to digitize the physical media in the access network (copper pairs, coax, satellite, microwave, fiber). All these tools support high speed MPEG-2-TS transport and/or high speed ATM transport. Clause 8 concerns the access-network-independent interface to the STU and provides a detailed specification of the physical interfaces between the network interface unit (NIU) and the STU. This physical interface can be internal or external to the Set Top Box (STB) and is independent from the physical interface used in the access network. It supports the transport of MPEG-2-TS and ATM between NIU and STU. Clause 9 concerns the STU dataport interface and specifies the physical interfaces used to connect an STB to various peripheral devices. It defines normative STU multimedia dataport tools and interfaces and also includes informative specifications for both PC and parallel dataports. These interfaces support the transport of MPEG-2-TS or IP. Clause 10 defines the physical interfaces for interconnections between cascaded SPS entities with or without an intervening core network and the physical interfaces for networks used to connect various hosts within an SPS.